Abrasive sleeve holder



a plurality of resilent arms l l.

Patented Oct. 4, 949

UNITED STATES PATENT OFFICE 2,483,422 ABRAsIvE sLEEvE HoLDER George A.Larson, Rockford, III.

Application May 15, 1946, Serial No. 669,869

8 Claims. 1

This invention relates to a rotatable holder whereon may be fitted anabrasive sleeve in the form of a fiexible endless band. In particular,the present improvements are concerned with the holder itself whichcomprises a rotatable hub from Which are extended a plurality ofresilient arms which at their outer ends, either directly or through themedium of a peripheral band, support a surrounding abrasive sleeve. Afeature of importance to this invention is the sleeve support which isyieldable so that, in response to a centrifugal force, it will tend tomove out thereby pressing itself tightly against the surrounding sleeve.Conversely, when motionless, the support contracts to a state ofrelaxation, the abrasive sleeve being then readily movable on or oif theholder.

In preferred forms the holders are cylindrical, even when not held tothat shape by the sleeve, and are reduced in size by twisting the sleevein one direction so that the sleeve may slip onto them easily in spiteof fitting tightly enough not to fall oif prior to reaching high speed.

Certain exemplifications of this invention are set forth in theaccompanying drawing in the manner following:

Figure 1 is a view in side elevation of a onepiece expansible holderfitted with a surrounding abrasve sleeve, shown as it appears whenmotionless;

Fig. 2 which is a similar view shows the holder and sleeve as whenrotated and pressed against the work;

Fig. 3 which is a view similar to Fig. 1 shows a holder having a hub,arms. and band formed of interconnected pieces;

Fig. 4 which is a view similar to Fig. 1, shows the holder made up of aband, and arms integral therewith, together with a hub to which the armsare removably connected; and

Fig. 5 which is also a view similar to Fig. 1, shows a one-piece holderof modified construction.

The present holder in each of its forms comprises a central hub Ill fromwhich is extended In each of the illustrated holders of Figs. 1 to 4,the arms are connected at their outer ends with a peripheral band l2.Through the center of the hub a bushing or shaft I 3 may be embedded toadapt the holder for attachment to a shaft or chuck (not shown) wherebyrotary motion is transmitted thereto. An abrasive sleeve S which isplaced around the holder is supported and driven thereby when the holderis in operation.

In the constructions of Figs. 1-2, the hub, arms, and band are shown asformed integrally of one piece of resilient material, such as rubbcr.The arms, while extended outwardly from the hub, are preferably curvedto provide arcuate end portions I4 which are concentric with the axis ofthe holder, these arcuate ends being extended alongside of the bandadiacent its inner face andv joined thereto at the arm extremities. Whenat rest, the holder will be relaxed, i. e. it will be neither contractedndr expanded, its diameter then being such that the abrasive sleeve maybe easily slipped on or off by twisting the sleeve in the direction inwhich the arms extend. When a rotary force is applied to its hub, thearms will be pulled around to transmit this force to the peripheral bandwhich tends to expand with increase in the centrifugal force that isdeveloped, the arms offering little or no resistance to this expandingmovement of the band. Since the abrasive sleeve is relativelynon-stretchable, the expanded band will press closely and tightlyagainst the inner face of the sleeve at every point whereby to establisha secure driving connection therewith. The sleeve may accordngly bedependd upon to rotate with the holder without slipping.

When pressed against a piece of work W, as suggested in Fig. 2, theperipheral band will tend to flatten at the point where engagement takesplace. lThere is accordngly a potential substantial area of contactbetween the abrasive sleeve and the work, instead of merely a linecontact as in cases where the holder is incapable of yielding.

A device of this character may be produced in various forms. Accordingto Fig. 3, the hub 20 is one part, the arms 21 while formed separatetherefrom are joined thereto, being anchored, as by cementing, in radialslots 25, and the peripheral band 22 upon its inner face is adhesivelyjoined to the extremities of the arcuate ends 24 of the arms 2! whichmay be extended therealong for an appreciable distance, as shown. Inoperation, exactly the same results take place. The hub, whether formedof plastic, Wood, metal or other material, is rotated to carry the armsforwardly thereby to rotate the peripheral band which expands undercentrifugal force to press tightly against the surrounding abrasivesleeve S.

In the showing of Fig. 4, the hub 30 is formed .with keyhole slots 36for receiving enlarged beads 31 at the inner ends of the arms 3'1, thelatter' intheir outer end portions 34 being curved to lie alongside theperipheral band 32 to which they are joined at their extremities,integrally or otherwise. An abrasive sleeve S may be fitted around theband, as shown. In this construction, the iimer ends of the arms may beslipped out of the keyhole slots, lengthwise thereof, so that the bendmay b e disassembled from the hub. The performance of this holder is thesame as the others already described.

According to Fig. 5, the hub 40 is provided with a plurality ofresilient arms 4! which initially may extend radially as indicated bythe dot and dash lines. In use, however, these arms are bent around tolie all in the same direction to provide curved outer end portions 44.Over the curved ends of these arms may be fitted an endless abrasivesleeve S which is supported thereby over an extended area, perhaps eventhe major part, of its inner surface. In this construction I dispensewith the peripheral band, relying instead upon the curved arm portionsin engagement with the f surrounding sleeve, to provide an adequatedriving support therefor. Viewed one way, the sleeve is itself a bandwhich may not always require for its support an inner band which isjoined to the arms; consequently, this form of holder may be foundentirely satisfactory for many purposes.

In all forms, the holder may be molded as one piece of rubber, beingmolded, except in Fig. 4, to a metallic shaft or spindle which may benurled or ribbed. It should be observed that the form of Fig. 5 isexceedingly simple to manufacture since the holders may be formed to thefinal shape with relatively simple molds.

All of the forms of the invention may be driven l in either direction.Ordinarily, it will be preferred to drive the holders in the directionin which the arms extend from the more radial portions thereof. Withthis direction of rotation the drag on the sleeve resulting from theabrasive use thereof will tend to flex the arms in such a manner as toincrease the force they exert against the sleeve. When a very softaction is desired, rotation in the opposite direction may be preferred.

It is important to have at least three and preferably four or more arms.With only two arms, very little pressure is required to push the sleeveoff center with respect to the aXis of the hub.

A salient characteristic of the present holder is its capacity to expandevenly under rotation so as to bear with pressure against thesurrounding sleeve. A Condition of expansion is normally attained whenthe holder is in operation, and a Condition of relaxation when theholder is still. This makes for security in the connection between theabrasive sleeve and the holder when the device is operated, and for easein removal of the sleeve and replacement of a substitute sleeve,whenever desired. In addition, the expanded peripheral band of theholder is susceptible of yielding when the sleeve is pressed against thework, so as to enlarge the area of its surface contact therewith.Accordingly, in many cases the time required for performing a given taskmay be materially reduced or the quality improved.

Successful performance of the present sleeve holder is also attributableto another factor, viz. the form and arrangement of the arms whichtransmit the rotary force to the surrounding sleeve. These arms, whileresilient, are stiff or self-sustaining enough to move the band throughits circular path, and not inwardly, the arms for a large part of theirlength being concentric therewith and adiacent thereto so thatcentrifugal force works on the arms. The connection between each arm andthe band, when a band is provided, is confined to a relatively smallarea at the arm extremity, leaving the arms and band elsewhere in freelyseparable relation. This is important in facilitating a uniform and evenexpansion or outward movement of the band at every point in itsperiphery when rotation takes place. The band is accordingly free toexpand at every peripheral point, even at the arm extremities whereconnection is made with the f band. In general these observations applyalso to the bandless construction of Fig. 5 in which frictionalengagement between the arms and sleeve is relied upon to transmitrotation to the latter. In every case the holder furnishes a rotatable,floating, yieldable, driving and concentric support for the abrasivesleeve such that it may be easily slipped on and off when motionless,and be fiattened somewhat at the point of its engagement with the workywhereby to enlargeits area of contact therewith.

The holder may, of course, .be made of synthetic rubber, such as thebuna rubbers, including Buna S, and neoprene as well as compounds ofnatural rubber. Any such materials may be deemed to be included in theterm rubber-like used in the claims, provided that they are flexible,compressible, elastic, and stable at slightly elevated operatingtemperatures, thus resembling Ordinary soft vulcanized rubber.

This application is a continuation in part of application Serial No.530,501, filed April 11, 1944:, now abandoned.

I claim: v

1. A rotary one-piece expansible abrasive sleeve holder of rubber-likematerial comprising a rotatable hub, a thin peripheral band concentrictherewith and spaced therefrom adapted to support a surrounding abrasivesleeve, and thin resilient arms fast to the band and extended outwardlyfrom the hub, and circularly adiacent the band in freely separablecontact therewith for distention thereof in connection with both the huband band to transmit rotary motion from the hub to the band whilepermitting expansive movement of the band against the surrounding sleevein response to centrifugal force, the entire flexibility of theresilient arms from the hub to the`outer ends of the arms being freelyavailable for radial expansion by centrifugal force, said arms extendingpredominantly in one circular direction so that with rotation in onedirection reaction of the work will tend to reduce the outward thrust ofthe arms, while with rotation in the opposite direction the reactionwill tend to increase said thrust, and said arms being also movableinwardly from the band to compensate for relative rotary movement of thehub and the band.

2. A rotary one-piece expansible abrasive sleeve holder of rubber-likematerial comprising a rotatable hub, a thin peripheral band concentrictherewith and spaced therefrom adapted to Support a surrounding abrasivesleeve, and thin resilient arms fast to the band and the hub andextended outwardly from the hub, forwardly with respect to its directionof rotation, and circularly adiacent the band in freely separablecontact therewith for distention thereof, in connection with both thehub and band to transmit rotary motion from the hubto the band whilepermitting expansive movement of the band against the surrounding sleevein response to centrifugal force, the entire flexibility of theresilient arms from the hub to the outer ends of the arms being freelyavailable for the expansion by centrifugal force, said arms havingapproximately the same cross sectional area as that of the band andbeing movable in- Wardly therefrom to compensate for relative rotarymovement of the 'hub and the band.

3. A rotary one-piece expansible abrasive sleeve holder of rubber-likematerial comprising a rotatable hub, a thin peripheral band concentricthere- With and spaced therefrom adapted to support a surroundingabrasive sleeve, and thin resilient arms having approximately the samecross sectional area as that of the band and fast to the band and thehub and extended outwardly from the hub, rearwardly with respect to itsdirection of rotation, and circularly adjacent the band in freelyseparable contact therewith for distention thereof, in connection withboth the hub and band to transmit rotary motion from the hub to the bandWhile permitting expansive movement of the band against the surroundingsleeve in response to centrifugal force, the entire flexibility of theresilient arms from the hub to the outer ends of the arms being freelyavailable for the expansion by centrifugal force, and said arms beingalso movable in'wardly from the band to compensate for relative rotarymovement of the hub and the band.

4. A rotary one-piece expansible abrasive sleeve holder comprising arotatable hub, a thin band concentric therewith and spaced therefrom,and thin arms having approximately the same cross Sectional area as thatof the band and joined at one end to the hub and elsewhere being curvedto extend along and adiacent the band and in connection therewith at theproximate arm ends, the hub, arms, and band being formed of one piece ofresilient material adapted to permit uniform expansion of the band inresponse to centrifugal force, the band, when in a condition of rest,having a normal diameter such as to receive thereon a relativelynon-stretchable abrasive sleeve, and when subjected to rotation, beingexpanded uniformlyV with pressure against the inner face of the sleeve,and said arms being also movable inwardly from the band to compensatefor relative rotary movement of the hub and the band.

5. A rotary expanding member including a hub, a thin resilientstretchable band concentric therewith and spaced therefrom, and thinarms insep- Y arably attached to the hub and 'band for driving the bandfrom the hub, the disposition and flexibility of the connecting meansbeing such as to allow the band to expand by centrifugal forcesubstantially without restraint from said connecting means, said armshaving outer portions located at spaced points around the band andextending circumferentially thereof and movable inwardly therefrom tocompensate for relative rotary movement of the hub and the band.

6. A rotary one-piece expansible abrasive sleeve holder of moldedresilient rubber-like material comprising a band having a cylindricalouter contour, a hub, spaced from the band, and at least three armsintegral With the band and the hub and supporting the band in its spacedrelation With the hub and having arcuate circumferentially disposedouter portions normally arranged contiguous to the band and disposed atspaced points around the same and movable inwardly from the band tocompensate for relative rotary movement of the hub and the band.

7. A rotary one-piece expansible abrasive sleeve holder of moldedresilient rubber-like material comprising a thin band having acylindrical outer contour, a hub, spaced from the band, and at leastthree thin arms integral With the band and the hub and supporting theband in its spaced relation with the hub and having substantially thesame cross sectional area as the band, said arms having curved outerportions normally in contact with the band and spaced at intervalsaround the same and movable inwardly from the band to compensate forrelative rotary movement of the hub and the band.

|8. A rotary expansible abrasive sleeve holder comprising a hub, a thinband having a cylindrical outer contour and spaced from the hub, and atleast three thin arms extending from the hub to the band and supportingthe latter in its spaced relation with the hub, said band and arms beingformed of one-piece of molded resilient rubberlike material and saidarms having substantially the same cross sectional area as the band andhaving outer arcuate portions normally arranged contiguous to the bandand spaced from one another and movable inwardly from the band tocompensate for relative rotary movement of the band and the hub.

GEORGE A. LARSON.

REFEREN CES CITED The following references are of record in the file ofthis pateu e UNITED STATES PA'I`ENTS Number

